1. Field of the Invention
The present invention relates to a chain including a first link and a second link located adjacent to each other in a longitudinal direction and coupled together via a pin in a bendable manner, and in particular, to the shape of the pin and the shape of a pin hole into which the pin is inserted.
The chain is, for example, a silent chain, and is used as a transmission chain in an automotive power unit.
2. Description of the Related Art
In a conventional chain of this kind, for example, a silent chain, a pin held in a pair of guide plates of the first link is inserted into a pin hole in a plurality of inner plates of the second link to connect the second link to the first link in a bendable manner (for example, Japanese Patent Application Laid-open No. H11-201238 (Paragraphs 0014 to 0017 and FIG. 1 and FIG. 2) and Japanese Patent Application Laid-open No. H8-68445 (Paragraphs 0010 and 0011 and FIG. 1 to FIG. 4).
In a chain in which, during chain bending when the second link bends relative to the first link, an outer peripheral surface of the pin held in the guide plates and a hole peripheral wall surface of the pin hole in the inner plates slide on the entire contact areas of the outer peripheral surface and the hole outer peripheral surface (for example, see Japanese Patent Application Laid-open No. H11-201238 (Paragraphs 0014 to 0017 and FIG. 1 and FIG. 2). In this case, the sliding makes the outer peripheral surface of the pin and the hole peripheral surface of the inner plate likely to wear progressively. Thus, disadvantageously, the chain becomes less durable, and power for driving the chain is subjected to a heavy frictional loss attributed to the chain.
In another chain, in addition to the pin held in the guide plates, another pin (see, for example, Japanese Patent Application Laid-open No. F18-68445 (Paragraphs 0010 and 0011 and FIG. 1 to FIG. 4); the pin corresponds to a bush in the roller chain) is inserted into the pin hole in the inner plates. In this case, the pin hole is larger, and thus, the inner plates have an increased size to ensure the rigidity of the plates. This leads to an increased chain pitch, making miniaturization of the chain difficult. Moreover, a plurality of pins is needed. This results in an increase in the number of pins and the number of assembly steps and the need to machine the plurality of pins in addition to the pin hole. Thus, chain costs disadvantageously increase.
The present invention solves these problems, and an object of the present invention is to provide a chain in which a hole peripheral wall surface of a pin hole in an inner plate into which a pin is inserted has a plate rolling surface that can roll on a pin rolling surface during chain bending, thus reducing friction caused by sliding between the pin and the inner plate, whereby durability is improved, a frictional loss is reduced, and the reduction in size and cost can be implemented.
Another object of the present invention is to provide a chain having improved applicability to rotary wheels with different winding diameters.